Magnetic ordering processes in manganese(II) di(hydrogen malonate) dihydrate complex studied by ESR spectroscopy

A new manganese complex of malonic acid CH2(COOH) 2źMnCO3źH2O was synthesized. Temperature dependence of the electron spin resonance (ESR) spectrum of Mn(II) was investigated in the 4.2-295 K. temperature range. The obtained ESR spectra were successfully fitted by using a Lorentzian-shape function. The fitting revealed existence of about 2% of a spurious phase of the manganese(II) complex. Strong magnetic interactions have been observed in the investigated temperature range with expected magnetic phase transition at TN approximately equals 2.5 K. The integrated intensity, linewidth and resonance field of the ESR spectrum have shown that the spin dynamical fluctuations essentially influence the magnetic system. An anomalous behaviour of the ESR resonance field parameter has been observed below 100 K. and with decreasing temperature the resonance field shifted to higher magnetic fields.